The present invention relates in general to automatic capping equipment.
Automatic capping equipment are machines that allow tightly to close threaded caps or stoppers on the mouth of containers to be packaged, for instance of the kind destined to contain food substances such as drinks. Although capping equipment are known which allow to close a single container at a time, capping machines are widely used which accomplish the operation of closing multiple caps on respective containers that travel along a circular trajectory, which capping machines are known as carrousel machines. More specifically, the invention relates to an automatic capping equipment provided with sterilisation means, having at least a rotary screwing head able to screw a cap onto the mouth of a container fed below the screwing head, in which the screwing head operates in a sterile area of the equipment and is supported by a related sliding support shaft, destined to be animated by an alternating motion, heating means being associated to each support shaft.
When capping equipment needs to be employed for packaging food substances susceptible to being contaminated as a result of contact with the outside environment, such as fruit juice based drinks or vegetable preserves, particularly in the case of products that do not contain preserving additives, the operation of closing the containers housing the product to be packaged must be performed under sterile conditions.
In the past, this was achieved by heating the product to be packaged to such a temperature as to allow its pasteurisation in order to guarantee its sterility.
However, it is well known that heating food products above a determined temperature can cause an alteration thereof, which leads to a reduction of their quality and of their nutritional characteristics.
To overcome this drawback, use is preferred of xe2x80x9ccoldxe2x80x9d packaging equipment in which the product to be packaged is only subjected to a fast heating, with a subsequent cooling, so as not to compromise its nutritional characteristics.
This is due to the fact that the containers with the product to be packaged are fed in an area in which a controlled atmosphere, pressurised with sterile air and previously sterilised with disinfectant substances such as peracetic acid 2% in solution, is present. The screwing head is immersed in this controlled atmosphere, which is usually located in a lower part of the capping equipment, so that it also remains under sterile conditions. However, the shaft that supports the screwing head, due to its alternating motion, can drag into the sterile area impurities coming from the upper part of the equipment (which is not immersed in the controlled atmosphere) in which are located the mechanical devices for the actuation of the screwing heads and the electrical and electronic control sets of the system. These impurities, penetrating into the sterile area where the containers are closed, could compromise the preservation of the sterility and integrity of the product to be packaged.
For this purpose, equipment has been devised that comprises a pressurised system able to supply steam at a temperature of about 120xc2x0 C. in correspondence with the support shafts in order to maintain them under sterile conditions to prevent impurities coming from other areas of the machine and dragged by the alternating motion of the support shaft from penetrating into the sterile area where the containers are closed, contaminating it.
Capping equipment provided with this steam supplying system, which requires the presence of a steam generator and pipelines to transport the steam to the areas to be sterilised, have a rather complex structure, hence costly to produce. Moreover, the pressurised steam used for heating the support shaft, after exiting the pipelines, does not remain localised in correspondence with the parts of the support shaft that penetrate into the sterile area, but is dispersed towards other parts of the equipment. In particular, after the steam performs its heating action on the shafts, it penetrates in the areas where the mechanical actuation devices and the equipment control sets are present, heating them. Such heating causes thermal expansions of the mechanical organs of the equipment, which can lead to warping in said organs with the consequent reduction of the operational reliability of the equipment and the need to perform more frequent maintenance operations with additional operating costs.
The aim of the present invention is to eliminate the aforesaid drawbacks and this is achieved by the equipment of the present invention, which is characterised by the content of the claims set out below and in particular in that the heating means are associated to each support shaft in correspondence with an operating part thereof which is proximate to the sterile area and are able to perform a heating action that is localised to said operating part of the shaft to maintain it at such a temperature as to guarantee its sterile condition and in such a way that the remaining part of each shaft is not substantially heated by the heating means.
The present invention concentrating heat on the area to be protected, unlike the steam that heats the whole turret as in the prior art, allows the application on the turret itself of electronic systems for controlling the capping operation, which allow for instance the automatic ejection of any bottles capped incorrectly.
Thanks to these characteristics, an effective sterility is guaranteed for the equipment area in which the operation of tightly closing the caps onto the related containers takes place, in a simple and reliable manner, without undesired impacts on the operation of other elements of the equipment.
Advantageously, the heating means include at least a resistive organ able to be connected with a source of electrical energy.
Preferably, the equipment further comprises temperature sensor means, the heating means and the temperature sensor means being associated to control means able to regulate in feedback the supply of electrical energy to the resistive organs by said source, according to the temperature measured by the sensor means.
In this way, the temperature of the part of the shaft that supports the related screwing head and that comes in contact with the sterile area of the equipment, can be controlled in optimal fashion so as to remain within a predetermined range, sufficient to guarantee the sterility of this part of the shaft. Thanks to this control which allows to optimise the quantity of heat supplied to each shaft, there is no generation of excess heat which, in addition to constituting a waste and hence an undesired cost, could be transmitted to other parts of the equipment with harmful consequences.